<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="div1">
        hello world!
    </div>
    <div id="div2">
        hello world!555555555
    </div>
</body>

<script>
    document.getElementById('div1').style.display = 'None'
</script>
</html>